KR100662489B1 - Method for fabricating multidomain lquid crystal display panel - Google Patents

Abstract

The present invention relates to a method for manufacturing a multi-domain liquid crystal panel to control the direction of incidence of light to the alignment layer by using a mask in which the structure is formed so that the light can be irradiated to the entire surface of the photoalignment layer at the same time. Forming an optical alignment layer on the upper substrate or the lower substrate, applying a mask on which the plurality of structures for controlling the refractive direction of incident light are formed on the optical alignment layer, and irradiating the light with the upper substrate and the lower substrate, In the manufacturing method of the multi-domain liquid crystal panel, comprising the step of bonding and injecting a liquid crystal between the two substrates, characterized in that the light is irradiated to the entire surface of the optical alignment film on the substrate. It is done.

Photo-Oriented, Multi-Domain

Description

Manufacturing method of multi-domain liquid crystal panel {METHOD FOR FABRICATING MULTIDOMAIN LQUID CRYSTAL DISPLAY PANEL}

1A to 1E are process drawings for explaining a method for manufacturing a multi-domain liquid crystal panel according to the prior art.

2 is a cross-sectional view for explaining a multi-domain liquid crystal panel manufacturing method according to the present invention.

Figure 3 is a cross-sectional view for explaining the size of the structure according to the present invention.

Figure 4 is a table showing the angle, refractive angle, δ of the structure according to the present invention.

5 is a cross-sectional view illustrating a distance relationship between a structure and a substrate according to the present invention.

* Explanation of symbols on the main parts of the drawings

21 substrate 22 photoalignment film

23: mask 24: structure

The present invention relates to a method for manufacturing a liquid crystal panel, and more particularly, to a method for manufacturing a multi-domain liquid crystal panel that realizes a multi-domain using optical alignment.

Liquid crystal display devices are attracting attention as the most competitive display that can replace CRTs because they have the advantages of light weight and low power consumption.

The liquid crystal panel of the liquid crystal display device is formed by injecting liquid crystal between the two substrates after the two substrates are opposed to each other to be spaced apart from each other by a predetermined interval, and uniform brightness and high contrast ratio are required in order to serve as a display. .

Therefore, the liquid crystal should be as uniform as possible. This is because the degree of alignment of the liquid crystal is an important factor that determines the superiority of the image quality of the liquid crystal display device.

The rubbing method or the photo-alignment method is mainly used for the alignment treatment to determine the degree of alignment as described above. The rubbing method includes one polyimide coating step, one photolithography step, and two rubbing steps for each of the upper and lower substrates. The production cost is increased because it has to go through a complicated process. In addition, since a photolithography process is included, it is difficult to secure the pretilt angle stability of the alignment layer and the reliability of the panel.

Thus, a photoalignment method has been proposed in which a photoalignment film coated on a substrate is irradiated with light to cause photoreaction (polymerization and decomposition) to induce rearrangement of the polymer to orient the liquid crystal.

Here, photo-alignment refers to a mechanism in which a photosensitive group bonded to a photosensitive polymer by linearly polarized ultraviolet rays causes a photoreaction and the main chain of the polymer is aligned in a predetermined direction, thereby aligning the liquid crystals.

Hereinafter, a manufacturing method of a liquid crystal panel will be described with reference to the accompanying drawings.

1A to 1E are flowcharts illustrating a method of manufacturing a multi-domain liquid crystal panel according to the prior art.

First, as shown in FIG. 1A, the optical alignment layer 12 is formed on the substrate 11 with a uniform thickness.

At this time, the pixels on the substrate are divided into regions I, II, III and IV.

Subsequently, as shown in FIG. 1B, the second, third and fourth domains (II, III, IV) are blocked using the mask 13, and then a light irradiation process is performed to remove only the first domain (I). 1 Make the pretilt angle.

At this time, the light irradiation is irradiated with polarized UV.

Next, as shown in FIG. 1C, the opening of the mask 13 is positioned on the second domain II, and the remaining part is masked, and then irradiated with light to form a second pretilt angle.

Subsequently, as illustrated in FIG. 1D, the mask 13 is shifted so that only the third domain III is exposed on the resultant product, thereby irradiating light to form a third pretilt angle.

As shown in FIG. 1D, the mask is moved to block the first, second, and third domains (I, II, and III), and then the light is irradiated onto the opening of the mask 13 on the fourth domain (IV) to provide a fourth light. A pretilt angle is formed.

Said light irradiation is made at least 1 time.

The liquid crystal panel formed by manufacturing the substrate in the same manner as described above implements four domains.

If one wants to form two domains, one light substrate is irradiated at least twice.

The pretilt angle will vary depending on the nature of the photoalignment film, the thickness of the photoalignment film, the light irradiation time or the light irradiation direction.

However, the conventional method of manufacturing a multi-domain liquid crystal panel as described above has a problem in that the total light irradiation time is long by irradiating light by dividing the mask by moving the mask in order to realize the multi-domain.

In addition, when one or more irradiations are required for one domain, when two-domains are used, the number of irradiation is increased since the number of irradiation is eight times.

The present invention has been made in order to solve the above problems, in the method of manufacturing a multi-domain liquid crystal panel which realizes a multi-domain of one light irradiation using a mask having a structure formed therein, a region in which light is not irradiated in any direction. The purpose is to minimize the light irradiation to the front of the photo-alignment layer.

The present invention for achieving the above object is a step of forming a photo-alignment film on the upper substrate or the lower substrate, and the step of irradiating light and covering the mask formed with a plurality of structures for controlling the refractive direction of the incident light on the optical alignment film And a step of bonding the upper substrate and the lower substrate to face each other, and a step of injecting liquid crystal between the two substrates, wherein the optical alignment layer on the substrate is formed. It is characterized in that the light can be irradiated to the front.

Hereinafter, a method of manufacturing a multi-domain liquid crystal panel according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view illustrating a method for manufacturing a multi-domain liquid crystal panel according to the present invention, FIG. 3 is a cross-sectional view illustrating the size of a structure according to the present invention, and FIG. 4 is a distance between the structure and the substrate according to the present invention. It is sectional drawing for demonstrating a relationship.

First, prepare an upper substrate and a lower substrate.

Next, a color filter layer is formed on the upper substrate, and a common electrode is formed on the color filter layer by using a transparent conductive film.

In addition, a gate line and a data line are formed on the lower substrate to form a unit to distinguish unit pixels, a thin film transistor is formed at an intersection point of the gate line and the data line, and is electrically connected to the thin film transistor. A pixel electrode occupying most of the unit pixel region is formed by using a transparent conductive film.

Subsequently, an optical alignment layer is coated on the upper substrate or the lower substrate with a uniform thickness. At this time, if it is not uniformly applied, it will be impossible to obtain a uniform pretilt angle during light irradiation in a later step.

The photo-alignment layer may include polyvinyl cinnamate, polysiloxane cinnamate, cellulose cinnamate, polyimide series, and the like, and any material suitable for the photo-alignment layer may be used. It's okay.

Then, the mask 23 is placed on the upper surface so as to correspond to the entire surface of the upper substrate or the lower substrate on which the photo-alignment film is applied, and light is irradiated once to form a pretilt angle.

As described above, after the alignment process is completed, when the upper substrate and the lower substrate are bonded to each other and the liquid crystal is injected between the two substrates, the desired liquid crystal panel is completed.

At this time, the mask 23 is a structure 24 is formed under the mask 23, as shown in Figure 2, the light is refracted by the structure 24 is not directly directed to the direction of the light is controlled. That is, when polarized light (ex, ultraviolet rays) enters the mask 23 and is emitted from the structure, the light is refracted by the refractive index of the projection material which is the material of the structure, and the light is irradiated toward the entire surface of the substrate 21 with a constant refractive angle. The photo-alignment film 22 is processed.

The above-mentioned light may use partial polarization, linear polarization, non-polarization, etc. in addition to polarization.

The structure 24 is formed using an organic projection material such as polymethymethacrylate (PMMA) or an inorganic projection material such as quartz or glass, and the angle θ of the structure 24 is greater than 90 ° to prevent total reflection. do.

In the following iii), ii) will be described in more detail for the structure as follows.

In this case, the structure is a triangular prism, and the direction of the light refracted by the first and second surfaces of the side surfaces of the triangular prism are the first and second directions, respectively. The structure has a third surface of the triangular prism formed in the mask.

Iii) The height of the structure 24 is p, the width of the structure 24 is 2r, and the refracted light is not irradiated with respect to one structure, as shown in FIG. 3, between the first and second directions. A region of is denoted as a, and x as a region where light refracted in the first direction is not irradiated and y as a region where light refracted in the first direction is irradiated, y,

The area where the light refracted by one structure is not irradiated in any direction is represented by

Can be expressed as:

이다. Also as shown in Figure 3,

to be.

이고, θ₁은 광의 굴절각이고, δ는 마스크에 대한 자외선의 입사방향과 구조물로부터의 자외선의 굴절방향이 이루는 각이다.At this time,

Θ ₁ is the angle of refraction of light, and δ is the angle between the direction of incidence of the ultraviolet rays to the mask and the direction of refraction of the ultraviolet rays from the structure.

Here, the structure angle θ, the refraction angle θ ₁ and δ of the light according to the structure material are represented by Snell's law as follows.

는 도 3 에 표시한 것처럼

이다.At this time,

As shown in Figure 3

to be.

4 illustrates a case where PMMA is used as a structure, and is a data value calculated by the third equation by substituting the refractive index n ₁ = 1.5 of PMMA and the refractive index n ₀ = 1 of air.

가 작아질수록 즉, 구조물의 각도(θ)가 커질수록 δ가 작아진다는 것을 알 수 있는데, 이는 광이 어느 영역으로도 조사가 되지 않는 a(=ptanδ)가 작아진다는 것을 의미한다.According to the data value,

It can be seen that the smaller 즉, that is, the larger the angle θ of the structure, the smaller δ, which means that a (= ptanδ), in which light is not irradiated in any region, becomes smaller.

Thus, the area a not irradiated with light is related to the angle θ of the structure and the height p of the structure.

Ii) As in FIG. 5, the BC 'length is h (ie, the distance from the mask to the height at which no light is irradiated) and the length between the photoalignment film 22 and C' is h '(ie, light is irradiated). Distance from the substrate to the substrate), which is related to the spacing (h + h ') between the structure and the substrate in order to minimize a region where light is not irradiated.

이고, △ABC'에서

이므로 That is, in ΔABC of FIG.

ΔABC '

Because of

In addition, h 'is obtained as follows.

In FIG. 5, since 2r: a = h: h ', using a = ptanδ and the fourth equation described in iii) above,

to be.

Accordingly, in the fifth equation, the distance h + h 'between the structure and the substrate is the height p of the structure, the width 2r of the structure, the angle of the structure θ, the angle of refraction of light depending on the material of the structure θ ₁ . It can be seen that the

Based on the contents in iv) and ii), the height of the structure (p), the width of the structure (2r), the angle of the structure (θ), the angle of refraction of light (θ ₁ ) according to the material of the structure and the distance between the structure and the substrate By properly adjusting (h + h '), the region a to which light is not irradiated can be minimized.

In addition, when the mask 23 having the triangular pillar structure 24 is formed as described above, light is refracted in two directions with respect to one structure 24 and irradiated onto the photoalignment layer 22, thereby forming a two-domain substrate ( 21) is formed.

If the structure is pyramidal rather than triangular, light is refracted in four directions to form a four-domain substrate, and if it is hemispherical, light is refracted in various directions to form a multidomain substrate.

The manufacturing method of the multi-domain liquid crystal panel of the present invention as described above has the following effects.

First, when manufacturing a multi-domain liquid crystal panel using optical alignment, a multi-domain can be realized by controlling the liquid crystal direction by controlling the direction of light with one light irradiation using a mask having a plurality of structures for controlling the refractive direction of incident light. And, since it is a one-time light irradiation, the process that the process is simplified has the effect of simplifying.
In addition, by adjusting the size of the structure or the distance between the mask and the substrate so that the light irradiation can be made to the entire surface of the optical alignment layer, there is an effect that the characteristics of the optical alignment layer is improved.
Second, in the case of a triangular prism-shaped structure, it is very effective to form a two-domain structure, and in the case of a hemispherical structure, there is an advantage that it can be oriented so that the boundary between the domain and the domain is not clear.

Claims (11)

Forming an optical alignment layer on the upper substrate or the lower substrate; Irradiating light with a mask on which the plurality of structures are formed on the photo alignment layer to control the refraction direction of incident light; Bonding the upper substrate and the lower substrate to face each other; In the manufacturing method of the multi-domain liquid crystal panel, comprising the step of forming a liquid crystal injection between the two substrates, The size, material, or distance between the mask and the substrate is adjusted to minimize the area to which light is not irradiated, and the area (a) where the light is not irradiated is a = ptanδ (where,

And θ1 satisfies the expression of the refraction angle of light according to the material of the structure), thereby minimizing the a value by adjusting the angle θ of the structure and the height p of the structure. The method of claim 1, wherein the structure is a polymethymethacrylate (PMMA). The method of claim 1, wherein the structure is quartz or glass. The method of claim 1, wherein the structure is any one of a triangular prism, pyramid, or hemispherical shape. delete The method of manufacturing a multi-domain liquid crystal panel according to claim 1, wherein the light is irradiated once. The method of claim 1, wherein the alignment direction of the liquid crystal is controlled by the direction of light by the structure. 8. The method of claim 7, wherein the alignment directions are different from each other. The method of claim 7, wherein the angle of the structure is greater than 90 degrees. delete The method according to claim 1, wherein the h 'value at the distance (h + h') between the mask and the substrate is minimized in order to minimize the region (a) where no light is irradiated.

and

Method of producing a multi-domain liquid crystal panel, characterized in that to satisfy the formula. Where h is the distance from the mask to the height at which no light is irradiated, h 'is the distance from the height at which the light is not irradiated to the substrate, and δ is the direction of incidence of ultraviolet light to the mask and the direction of refraction of ultraviolet light from the structure As an angle

Θ1 is the angle of refraction of light depending on the material of the structure, θ is the angle of the structure, p is the height of the structure and 2r is the width of the structure.

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